As related-art open-door running prevention units for a hydraulic elevator, there have been proposed a braking method using an emergency stop device (see, for example, Patent Literature 1), a method using a dual check valve (see, for example, Patent Literature 2), and the like.
Each of the open-door running prevention units monitors a position of a car or a speed of the car in an open-door state to determine an abnormal state and performs a braking operation for the car.